1. Field of the Invention
This invention relates generally to the field of data processing and more particularly to binary coded decimal arithmetic operations performed by binary apparatus.
2. Description of the Prior Art
Data processing systems execute arithmetic and logical instructions. These instructions call for operands having different characteristics. Operands may include, typically, binary words of various bit lengths, bytes, ASCII characters, 4-bit digits, 6-bit digits, and binary coded decimal digits. The digit operands may be packed or unpacked, and include or not include zone bits.
A data processing system may be designed to perform arithmetic operations on one or more types of operands by using arithmetic units and switches of varying complexities with resulting increased cost. Some data processing systems are designed for just binary arithmetic; others are designed to process bytes or binary coded decimal operands. Cost and efficiency of operation are always a factor in determining the characteristics of the hardware to execute arithmetic and logical operations on types of operands.